1. Field of the Invention
The present invention relates to an apparatus for unrolling and sharpening a cutting edge on a blade that has its edges rolled or dulled. More specifically, the invention is directed toward improvements including top guide rails and the rear spring caps in such an apparatus. The invention includes improvements to the structure of the slot at the opening, including angled guide rails, and also, the resilient springs are more versatile and can be used in both flanges, each rear spring cap is only properly insertable in one side of the base due to their shape, and the pin rods and their relation to the base have been improved.
From time to time it becomes necessary to straighten, realign and sharpen the microscopic edge of a cutting tool such as a knife. During use, the edge of a blade becomes rolled or turned from direct contact with hard objects. It is important to maintain a uniform pressure and a proper even edge angle when sharpening a cutting edge. Previous sharpening devices have involved complex implements that commonly remove material from the cutting edge. Additionally, many of the previous devices are designed for use either only by a right-handed or left-handed person while sharpening one side of the edge at a time, not both. The present invention relates to a sharpener having a substantially enclosed versatile biasing assembly that resists contamination during use and provides for outstanding cleaning.
2. Description of the Prior Art
U.S. Pat. No. 5,478,272 owned by applicant herein describes apparatus for sharpening a cutting edge on a blade. The invention disclosed herein addresses specific improvements to that
U.S. Pat. No. 5,478,272 owned by applicant herein describes apparatus for sharpening a cutting edge on a blade. The invention disclosed herein addresses specific improvements to that apparatus. Although that apparatus successfully sharpens blades, the top portion could become worn through careless contact by the blade to be sharpened. Also, in replacing worn parts, the sharpening members could be installed backwards, and the stop members were difficult to remove because they did not pass through the entire base.
Earlier devices for sharpening blades fall into three broad categories: (a) devices having sharpening elements in permanent fixed relationship such as that disclosed in U.S. Pat. Nos. 578,440; 1,851,520; 1,909,743; 2,767,530 and 5,163,251; (b) devices having sharpening elements in movable relationship to each other with fully exposed biasing assemblies such as that disclosed in U.S. Pat. No. 4,934,110; and (c) devices having sharpening elements in movable relationship to each other with biasing assemblies not shielded from debris such as that disclosed in U.S. Pat. Nos. 1,041,631; 1,570,083; 2,124,646; 2,885,836; 4,550,632; and 4,624,079 as well as Patent Nos. GB 293,785 and GB 517,242.
There are problems and limitations with all of these earlier devices. Devices having sharpening elements in fixed relationship to each other are relatively inefficient, needing considerably more resistance when passing a blade between the elements in order to sharpen the blade and may not provide optimal sharpening of the blade. These arrangements often remove perceptible metal fragments from the blade, which shortens the useful blade life and is undesirable for contamination reasons.
In movable element arrangements, exposed biasing means, such as counterweights, lever arms, springs and the like, are prone to collect food particles and other debris during use. These sharpening devices are often used in food processing plants where the blades to be sharpened are full of meat particles. Where the spring is not shielded from debris that may accumulate during use, this condition can cause related problems of contamination and disease.
In certain food industries, governmental authorities regulate and inspect the processing of food for sale to consumers. While many sharpening devices produce a sharp blade, these prior devices have disadvantages of exposed parts or configurations that collect debris and contribute to the problems of contamination and disease. Additionally, cleaning the exposed parts of known devices is costly as these require specific attention to the meshed windings of springs and counterweights and the like. Cleaning may require disassembly of the housing in order to clean the apparatus and remove the debris. Sometimes when an operator is using prior art devices, the operator may be of the misconception, in not seeing the debris that is collecting, that all is well and the apparatus does not need cleaning, which in fact is not the case. Thus, there is a need for a blade sharpening apparatus of the present invention that eliminates operator error due to unseen contamination, reduces cleaning and maintenance costs, and eliminates contamination thereof.
Accordingly, it would be desirable to provide an improved blade sharpener. It has therefore been found beneficial to produce a blade sharpener with top guide rails at the upper end of the slot opening, springs that are more versatile and can be used in both flanges, improved rear spring caps that are only properly insertable due to their shape, and improved stop members that completely pass through the base.